TNNT2 encodes cardiac troponin T, the tropomyosin-binding subunit of the thin filament regulatory complex that confers calcium-sensitivity to cardiac muscle contraction 1. As a component of the troponin complex, TNNT2 regulates striated muscle actomyosin ATPase activity and participates in sarcomere organization and cardiac myofibril function. Pathogenic TNNT2 variants cause three forms of inherited cardiomyopathy: hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and restrictive cardiomyopathy 2. TNNT2 is classified as a definitive HCM disease gene 3 and accounts for approximately 29% of genetic HCM cases in population studies 4. TNNT2 variants show high penetrance (~60%) in HCM families, with mean disease onset at 38 years 5. Recent mechanistic studies demonstrate that DCM-associated TNNT2 variants disrupt sarcomere-mitochondrial communication by weakening cTnT interaction with 14-3-3 proteins, triggering excessive mitochondrial fragmentation through aberrant RAS/RAF1-p44/42 kinase signaling 6. Notably, TNNT2 variants are associated with more severe clinical outcomes in children with cardiomyopathy 2, underscoring the clinical importance of genetic testing and early diagnosis for patients with TNNT2 mutations 7.